The present invention relates to information display systems and, more particularly, an improved mechanism for extending and retracting an image combiner that is attached to the helmet worn by an aircraft pilot.
1. Review of the Prior Art
Sometimes it is necessary for aircraft pilots to simultaneously view both the exterior scene within the normal field of vision and information provided by an information display system. "Heads up" displays can be achieved through the use of a combiner mechanism, which can be a part of the aircraft or can be a part of the helmet worn by the user, as taught in Ellis, U.S. Pat. No. 4,364,636, and Baldwin, U.S. Pat. No. 3,170,979. However, as pointed out in Ellis, the device in Baldwin is not capable of being used with a visored helmet, which is essential for military aircraft pilots and observers.
When dealing with helmet mounted displays, it is desirable that the combiner, if not in place at all times, be deployed quickly, or automatically, by means of a remote control. Neither Ellis nor Baldwin teaches a device with this capability. Thus, neither is well-suited to ensure quick, reliable deployment and retraction of the combiner in a variety of situations, especially in times of emergency.
2. Summary of the Invention
The purpose of the present invention is to provide a helmet mounted combiner mechanism which can be automatically and rapidly deployed and retracted by various means, preferably without the use of hands. A preferred embodiment of the present invention uses a combination of conventional springs, together with springs made from shape memory alloy ("SMA"). A spring made from an SMA material such as a Nickel-Titanium ("NiTi") alloy can first be deformed and later be caused to "remember" its original shape by the application of heat. While heat can be applied from many common sources, such as a flame, steam or radiant heat, in the preferred embodiment an electrical current is passed through the spring and which heats the spring due to the electrical resistance of the spring wire. Once the SMA spring is heated, it is able to exert a greater force than a countervailing conventional spring, which normally exerts the greater force. By selectively applying heat using the SMA springs, a combiner can automatically be deployed or retracted without the need for the pilot to touch the mechanism.
Other deployment and retraction means taught herein include solenoids or similar devices, and electrical motors which are used in conjunction with a SMA type spring.
In summary, the present invention finds its main use in the cockpit of a modern military aircraft wherein a pilot's attention and hands are totally engaged in monitoring and controlling the plane. This device allows a pilot to automatically deploy a combiner into his viewing area. This can be accomplished without the pilot having to actually touch the combiner. Also, this may be accomplished without the need to move or modify the pilot's visor. In the event that the pilot does not need to use the combiner, he can remotely activate the invention's retraction feature. This is particularly advantageous in emergency situations when a pilot must act quickly to clear his field of view.
An apparatus constructed in accordance with the present invention includes, in combination, a bracket attached to a pilot's helmet, a combiner arm being rotatably mounted on the bracket, means to select either a deployed position or retracted position for the combiner, means to automatically deploy and lock the combiner into position to be viewed by the pilot and means to automatically retract and lock the combiner out of the view of the pilot.
The novel features which are characteristic of the invention, both as to structure and method of operation thereof, together with further objects and advantages thereof, will be understood from the following description, considered in connection with the accompanying drawings, in which the preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only, and they are not intended as a definition of the limits of the invention.